merge ethereum bug fix : core: fix chain indexer reorg bug #19748

PR:ethereum/go-ethereum#19748

Git commit: https://github.com/ethereum/go-ethereum/pull/19748/files/48c9d284c17d444b2b13aae857883ed58d22eb3e

blockchain/chain_indexer.go

@@ -256,6 +256,7 @@ func (c *ChainIndexer) updateLoop() {
 					updated = time.Now()
 				}
 				// Cache the current section count and head to allow unlocking the mutex
+				c.verifyLastHead()
 				section := c.storedSections
 				var oldHead common.Hash
 				if section > 0 {
@@ -270,7 +271,7 @@ func (c *ChainIndexer) updateLoop() {
 				c.lock.Lock()
 
 				// If processing succeeded and no reorgs occcurred, mark the section completed
-				if err == nil && oldHead == c.sectionHead(section-1) {
+				if err == nil && (section == 0||oldHead == c.sectionHead(section-1)) {
 					c.setSectionHead(section, newHead)
 					c.setValidSections(section + 1)
 					if c.storedSections == c.knownSections && updating {
@@ -286,6 +287,7 @@ func (c *ChainIndexer) updateLoop() {
 				} else {
 					// If processing failed, don't retry until further notification
 					c.log.Debug("Chain index processing failed", "section", section, "err", err)
+					c.verifyLastHead()
 					c.knownSections = c.storedSections
 				}
 			}
@@ -334,13 +336,27 @@ func (c *ChainIndexer) processSection(section uint64, lastHead common.Hash) (com
 	return lastHead, nil
 }
 
+
+
+// verifyLastHead compares last stored section head with the corresponding block hash in the
+// actual canonical chain and rolls back reorged sections if necessary to ensure that stored
+// sections are all valid
+func (c *ChainIndexer) verifyLastHead() {
+	for c.storedSections > 0 {
+		if c.sectionHead(c.storedSections-1) == GetCanonicalHash(c.chainDb, c.storedSections*c.sectionSize-1) {
+			return
+		}
+		c.setValidSections(c.storedSections - 1)
+	}
+}
+
 // Sections returns the number of processed sections maintained by the indexer
 // and also the information about the last header indexed for potential canonical
 // verifications.
 func (c *ChainIndexer) Sections() (uint64, uint64, common.Hash) {
 	c.lock.Lock()
 	defer c.lock.Unlock()
-
+	c.verifyLastHead()
 	return c.storedSections, c.storedSections*c.sectionSize - 1, c.sectionHead(c.storedSections - 1)
 }